package JZ.topic1;

import java.util.Arrays;

/**
 * 输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。
 */
public class T_04_reConstructBinaryTree {
    public TreeNode reConstructBinaryTree(int[] pre, int[] in) {
        if (pre.length == 0 || in.length == 0) { //此处判断的要是数组长度
            return null;
        }
        if (pre.length != in.length) {
            return null;
        }
        TreeNode root = new TreeNode(pre[0]);
        for (int i = 0; i < pre.length; i++) {
            if (pre[0] == in[i]) { //此处要是 in[i]
                root.left = reConstructBinaryTree(Arrays.copyOfRange(pre, 1, i + 1), Arrays.copyOfRange(in, 0, i));
                root.right = reConstructBinaryTree(Arrays.copyOfRange(pre, i + 1, pre.length), Arrays.copyOfRange(in, i + 1, in.length));
            }
        }
        return root;
    }
}
